Due to the increase in morbidity and mortality from Chronic Obstructive Pulmonary Disease (COPD), a group of chest physicians updates the basic knowledge on COPD since the last Consensus in 1994 in order to prepare guidelines for its diagnosis, prevention and treatment. The authors review the definition of COPD together with the most recent information on its pathophysiology. The clinical presentation is summarized together with functional evaluation and imaging. Early diagnosis by means of functional testing (i.e., spirometry) is stressed, emphasizing smoking cessation as the only measure that has been shown to alter the outcome of the disease. Smoking cessation strategies are described as well as pharmacological and non-pharmacological treatment. In the pharmacological section, the use of inhaled bronchodilators (anticholinergic, beta 2 adrenergic agonists or both) is considered the first option for treatment. Long acting bronchodilators improve patient compliance and treatment effectiveness. Inhaled corticosteroids are indicated for patients with severe airways obstruction and known response to corticosteroids. These agents can diminish the number of exacerbations. Annual influenza vaccination is recommended in all patients. In the non-pharmacological section, surgery for emphysema is suggested in particular cases. Rehabilitation, including exercise training, kinesitherapy and nutrition, is a useful tool for patients who are physically disabled. Long-term oxygen therapy at home improves survival in patients with severe chronic hypoxemia. Other therapeutic interventions such as non-invasive home ventilation have specific indications. Acute exacerbations must be aggressively treated with oxygen, corticosteroids, antibiotics, combination of bronchodilators, and eventually respiratory support. The role of public education of the patients and their families is essential in the prevention and treatment of the disease.